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(No Model.) 2 SheetsSheet 14 F. G. PERKINS & J. D. KILLIP.

AUTOMATIC ELECTRIC SWITCH Patented Feb. 8, 1898.

Pl tines; e;

(No Model.) 2 SheetsSheet 2.

F; O. PERKINS & J. D. KILLIP.

. AUTOMATIC ELECTRIC sWITeH.

Patented Feb. 8, 1898.

a v/AZ UNITED STATES PATENT QFFICE.

FRANK C. PERKINS AND JOHN D. KILLIP, OF BUFFALO, NEW YORK; SAID KILLIPASSIGNOR TO SAID PERKINS.

AUTOMATIC ELECTRIC SWITCH.

I SIPEGIFICATION forming part of Letters Patent No. 598,715, datedFebruary 8, 1898.

Application filed September 25, 1897. Serial No. 652,997. (No model.)

To aZZ whom it may concern.-

Be it known that we, FRANK O. PERKINS and JOHN D. KILLIP, citizens ofthe United States, residing at Buffalo, in the county of Erie and Stateof New York, have invented a new and useful Improvement in AutomaticElectric Switches, of which the following is a specification.

This invention relates to the class of electric switches or cut-outswhich automatically break the circuit when the strength of the currentbecomes excessive or rises above the normal owing to short-circuiting oroverloading, thus preventing burning out or other injury to theelectrical apparatus in the circuit.

The object of our invention is to simplify the construction of suchswitches and reduce their cost of manufacture.

In the accompanying drawings, consisting of two sheets, Figure 1 is afront View of our improved switch, showing the same closed. Fig. 2 is aside elevation thereof. .Fig. 3 is a view of the front end'of theswitch, partly in section, the plane of the sectional portion being inline 3 3, Fig. 1. Fig. 4 is a vertical section of the lower portion ofthe switch, showing the pointer on the locking-lever and the scale withwhich it cooperates. Fig. 5 is a transverse vertical section of thelower portion of the switch. Fig. 6 is a front view of the lower portionof the switch, showing a modification of the locking-catch and thespring for automatically opening the switch. Fig. 7 is a transversesection in line 7 7, Fig. 6. Fig. 8 is asectional front view of anothermodification of the switch.

Like letters of reference refer to like parts in the several figures.

A is the base of the switch, which may be made of any suitablenon-conductin g material, such as slate.

B B are the metallic arms or members of the usual double switch-lever,which members are pivoted at their upper ends to lugs c, secured to thebase A, and are connected at their opposite ends by a non-conductingcross-bar B, having a handle B The switchlevers B are adapted to enterbetween the usual stationary contact-j aws or elastic plates 0 O,secured to the base.

01 d are the line-wires, which are secured in sockets D D, formed on orsecured to the lower pair of contact-plates 0.

Referring to the construction shown in Figs. 1 to 5, E is a catch ornotched arm extending inwardly from the cross-bar B'of the switchleverand adapted to interlock with a locking lever F for retaining theswitch-lever in its closed position. The locking-lever is bent orelbow-shaped and pivoted by a horizontal pin fto the base of one of thelugs c or to the base-plate A, so that its lower vertical portion fswings laterally between the upper and lower pairs of stationarycontact-plates 6 5 O O. The catch E engages in an opening f formed inthe locking-lever, and the nose of the catch is beveled, as shown, so asto interlock automatically with the edge of said opening upon closingthe switch-lever.

G G are springs which automatically open the switch-lever when the sameis released, so as to break the circuit and cut out the electricalapparatus controlled by the switch. In the construction shown in Figs. 1to 5 curved springs are employed, which are secured at their upper endsto the base and engage with their free lower ends under lateralprojections or extensions h of the cross-bar B, these springs beingstrained in the closed position of the switch-lever, so as to throw thelever outward by their reaction the instant the lever is released.

I is a thermal rod, wire, or resistance included in the switch-circuitand arranged to retract or actuate the locking-lever F when the strengthof the current rises above the normal, so as to disengage thesame fromthe locking-catch E of the switch-lever and allow the springs G to openthe lever. This rod or wire is secured at one end to a fixed socket orholder J, fastened to the base of the adjacent lug 0, while its oppositeend is connected with the upper short arm f of the lockinglever F, thewire being preferably fastened 95 in its sockets by set-screws 71; 70.When the switch is closed, the current entering the branch 61 of theline-wire passes through the right-hand contact-plates O C andthe-righthand switch-lever B, and thence through the holder J, thermalwire I, the upper arm of the locking-lever F, and the left-handswitchlever B to the other branch d of the line-wire.

The thermal wire becomes heated by the passage of the current andexpands gradually as the strength of the current increases; but it ismade of such a size or diameter that it does not expand sufficiently tooperate the locking-lever F so long as the current remains normal; butas soon as'the strength of the current exceeds the normal from any causethe increased expansion of the wire resulting therefrom causes the lowerarm f of the locking-lever to swing in the direction of the arrow inFig. 1, disengaging the same from the catch E of the switch-lever andallowing the springs G to throw the latter to its open position, thusautomatically breaking the circuit and preventing injury to theelectrical apparatus.

Any suitable material may be employed for the thermal wire, such asGerman silver, iron, copper, nickel, or other metals.

Upon loosening one or the other of the setscrews k k the locking-levercan,be adjusted to interlock with the catch E under normal conditions,the set-screws being again tightened after effecting the adjustment.

constructed of spring-steel and is sufficiently elastic to allow thebeveled nose of the catch to engage automatically therewith upon closingthe switch-lever.

The resistance formed by the thermal wire the same thermal wire may beused for cur- 5 rents of different strength by adjusting the 5 wirelengthwise in one of its sockets relatively to the other, so as toincrease or reduce the effective length of the wire, thereby requiring acorrespondingly greater or less degree of expansion of the wire toactuate the locking-lever. In this case the locking-lever is adjusted toenter the notch of the catch E a greater distance for a high current anda shorter distance for a low current. WVe prefer to adjust the end ofthe wire secured in the holder J, and in order to permit a fine itslower end may be provided with a pointer or index on, which traverses asuitably-graduated scale m, secured to the base, as most clearly shownin Fig. 4. This scale and the pointer are not essential and may beomitted, if desired.

The lower arm of the locking-lever is preferably The thermal wire ispreferably inclosed by a tube or jacket I, of miconite, glass, or othersuitablenon-conducting material, to confine the heat and insulate thewire.

When the switch is used in connection with a comparatively low or weakcurrent requiring a correspondingly thin thermal wire, the wire isliable to bend or buckle when the current strength exceeds the normalinstead of remaining stiff and operating the locking-lever. To insurethe tripping and opening of the switch with the use of such a thin wire,a spring N, Fig. 8, may be employed, which operates upon the long arm ofthe lockinglever and tends constantly to shift the same in the properdirection to disengage it from the catch of the switch-lever. Either atension or a compression spring may be used for this purpose. In thedrawingsa compressionspring is shown. This spring is compressed when thethermal wire is cold, and when the wire expands to an abnormal degree itallows the spring to shift the lever and trip the switch for breakingthe circuit. Such a spring may also be used in connection with heavycurrents, in which case a fiat expansion-strip may be substituted forthe thermal rod or wire, if desired.

As a modification of the switch-opening de-* vice a single spring G,arranged underneath the cross-bar B of the switch-lever, may besubstituted for the two springs G. In this case the spring is incased ina barrel or housing 0, secured to the base A, and the cross-bar B isprovided with a projecting stemp, which bears against a follower 19,hearing in turn against the outer end of the spring in the closedposition of the switch. In this modification the locking-catch consistsof a lever E, pivoted between its ends to the left-hand side of thespring-housing 0 .and having at its upper end a hook or nose, whichinterlocks with a flange or shoulder q of the stem p. The lower arm ofthe catch E faces the locking-lever F. hen the locking-lever is actuatedby an excessive current, it trips the catch E, causing the latter torelease the switch-lever and allowing the spring G to throw the lever toits open position.

Our improved switch is simpler than switches in which an electromagnetis used for controlling the lock of the switch-lever, and it can beproduced at less cost than such a switch.

We claim as our invention 1. In an automatic electric switch, thecombination with a base having 'a contact, of a switch-lever arranged toswing at right angles to the base, a locking-lever pivoted to swingparallel with the base and adapted to interlock with said switch-leverfor holding the same in its closed position, an expansible thermal rodor wire included in the circuit and secured at one end to the base andoperating at its opposite end upon said lockinglever, and automaticmeans for opening the switch-lever when released, substantially as setforth.

2. In an automatic electric switch, the combination with a base having acontact, of a switch-lever arranged to swing at right angles to the baseand provided on its inner side with a catch extending toward the base, alocking-lever pivoted to swing parallel with the base and interlockingnormally with said catch, an expansible thermal rod or wire arrangedsubstantially at right angles to the switch-lever and having one endthereof secured to the base and its opposite end connected with saidlocking-lever, and automatic means for opening the switch-lever whenreleased, substantially as set forth.

3. In an automatic electric switch, the combination with a base havingtwo sets of contacts, of a double switch-lever arranged to swing atright angles to the base and having its members connected by a cross-barwhich is provided on its inner side with a catch extending toward thebase, a two-armed locking-lever arranged between the two sets ofbase-contacts, pivoted to swing parallel with the base and adapted tointerlock with said catch, an eXpansible thermal rod or wire arrangedtransversely above the double switchlever and having one end thereofsecured to the base and its opposite end connected with the upper arm ofsaid locking-lever, substantially as set forth.

4. 'In an automatic electric switch, the combination with a base havinga contact, of a switch-lever arranged to swing at right angles to thebase and provided on its inner side with a catch extending toward thebase, a locking-lever pivoted to swing parallel with the baseinterlocking normally with said catch, and provided with a pointer, ascale mounted on the base and traversed by said pointer, an expansiblethermal rod or wire included in the circuit and controlling saidlocking-lever, and automatic means for opening the switch-lever whenreleased, substantially as set forth.

Witness our hands this 16th day of September, 1897.

FRANK O. PERKINS. JOHN D. KILLIP.

Witnesses:

CARL F. GEYER, KATHRYN ELMoRE.

